A route is used for transmitting data from source terminal equipment in a communications network to destination terminal equipment through a router. When data packets are transmitted, the router needs to select an optimal path and switch the data packets in the route maintained by the router. Metric is a calculation standard for determining the optimal path to reach the destination terminal equipment in a route algorithm. For example, in the standard, the optimal path can be determined with the shortest path or the smallest path overhead. In order to enable the router to select the path after the data packets are received, route initialization needs to be performed and a routing table including path information in the communications network needs to be maintained. The path information varies with different route algorithms that are used. A manner in which the router is informed of the path information of the destination terminal equipment or a next hop router is that the path information is issued in the communications network (can be issued by the router). After receiving the path information, the router can attempt to communicate with other routers or destination terminal equipment according to the received path information, so as to establish the routing table for forwarding the data packets for the router itself. The established routing table includes all kinds of information such as distance information, information of the hop count to reach the destination terminal equipment, and address information of the next hop. Likewise, Metric varies with different route algorithms that are used. After receiving data carrying a destination address, the router selects, according to the carried destination address, the optimal path to transmit data packets to the next hop router or destination terminal equipment in a routing table that adopts Metric. For example, Metric determines the optimal path according to the shortest path. At this time, after selecting, according to distance information in the routing table, a path with the shortest distance to reach the destination address as the optimal path, the router can transmit the data packets to the next hop router or destination terminal equipment.
In this way, the routers communicate with each other, and maintain and update their own routes by exchanging the path information. The maintenance and update of their own routes are generally maintaining and updating a routing table including all or partial information, and a network topology view is established by analyzing path information from other routers or terminal equipment. Transmission of the path information among the routers can further adopt a mode of sending broadcast information in a linked state. The routers notify a linked state of other routers sending the broadcast information. The linked state information is used for establishing a complete topological view, so that the routers can determine the optimal path when transmitting data packets.
When the routes are deployed in the communications network, a multi-homing technology and a traffic engineering technology are adopted. The multi-homing technology is for link survivability or load balance. A link group with more than one link is established between the terminal equipment and a backbone network of the communications network. The link group with more than one link may belong to the same operator or different operators. The traffic engineering technology is actually a suit of tools and methods adopted by the communications network. Regardless of whether the terminal equipment and transmission lines in the communications network are normal or failed, an optimal service can be extracted from the configured communications network, which can optimize allocated resources. With the establishment of the communications network based on the multi-homing technology and wide deployment of the traffic engineering technology in the communications network, the number of routes in one communications network increases quickly, which leads to the following results. On the one hand, in a router a larger capacity storage routing table needs to be set, which results in cost increase. On the other hand, due to the large number of routes maintained by the router, route convergence of the router becomes slow, that is, a rate of route processing on data becomes slow, which results in a reaction rate of data transmission of the communications network becomes low and work efficiency of the entire communications network is influenced.
In order to solve the foregoing problems, a core-router integrated overlay (CRIO) technology is proposed in the communications network. FIG. 1 is a schematic structural view of a network adopting the CRIO technology to maintain routes in the prior art, where the network includes a transmission network and edge networks. Different edge networks are connected through the transmission network. The transmission network includes one or more point of presence (PoP) nodes. An edge network includes terminal equipment. A border router is included at a boundary between the transmission network and the edge network. In FIG. 1, for simplicity, one PoP node is shown.
Routes maintained by different PoP nodes are routing information of different super prefixes and routing information of a detailed prefix covered by the super prefixes. The different PoP nodes issue the routing information of the maintained super prefix in the transmission network. However, the routing information of the detailed prefix covered by the super prefix does not need to be issued. Border routers of autonomous systems (AS's) and other core routers in the transmission network do not need to maintain all routing information of the detailed prefix covered by the super prefix and only need to maintain routes of the super prefix.
Here, the routing information of the super prefix can also be referred to as converged routing information.
Here, the routing information of the detailed prefix covered by the super prefix is routing information in the edge network related to the super prefix.
The terminal equipment accesses the transmission network through the border router. When data packets are transmitted, source terminal equipment sends the data packets to a source end border router. According to stored routing information of the super prefix corresponding to a destination address, the source end border router sends data to a PoP node maintaining the routing information of the super prefix. The PoP node determines a path through the maintained routing information of the detailed prefix covered by the super prefix, so as to establish a tunnel between the PoP node and a destination end border router. The data packets are forwarded to the destination end border router through the tunnel. The destination end border router forwards the data packets to destination terminal equipment according to routing information stored by the destination end border router itself.
In practical applications, the transmission network may be a backbone network of the Internet, and the PoP node may be a super router or a host.
A basic idea of adopting the CRIO technology in a network is how to reduce route capacity of the backbone network of the Internet. It is found, based on a model of flow of practical transmission data of the Internet, that flow of data sent to the terminal equipment corresponding to a few network segment addresses occupies a large portion of bandwidth. Therefore, during transmission, the terminal equipment that transmits data packets with less flow can increase the hop count to reduce the route capacity of the backbone network of the Internet. A basic realization idea is to change a mesh routing structure of the Internet into a tree routing structure. As shown in FIG. 1, the routing information of the super prefix is issued only through the PoP nodes in the backbone network of the Internet while the routing information of the detailed prefix covered by the super prefix is not issued in the backbone network of the Internet. A border router of the backbone network of the Internet provides the routing information of the detailed prefix under the super prefix to a PoP node dominating the routing information of the super prefix and the PoP node stores the routing information of the detailed prefix.
In this way, other routers or equipments in the backbone network of the Internet only need to maintain the routing information of the super prefix and no longer need to maintain lots of routing information respectively, so that the route capacity of the backbone network of the Internet is reduced.
When data packets are forwarded, the data packets are first forwarded to a PoP node that issues the routing information of the super prefix. The PoP node saves the routing information of the detailed prefix covered by the super prefix, finds a corresponding detailed prefix route by searching the mapping relation, then establishes a tunnel between a PoP node and the border router corresponding to the detailed prefix route according to the detailed prefix route, and forwards the foregoing data packets to the border router through the tunnel.
Advantages of establishing and maintaining routes in the communications network by adopting the CRIO technology are as follows. Because other routers in the transmission network only need to maintain the routing information of the super prefix and do not need to maintain all routing information of the detailed prefix covered by the super prefix, the number of routes maintained by most routers is significantly reduced in the transmission network, processing burden and oscillation during data transmission in the communications network by adopting the Border Gateway Protocol (BGP) are reduced, and convergence of BGP routes is accelerated.
In a process of implementing the present invention, the inventor finds that the prior art has at least the following problems.
Because all the data packets to be transmitted in the communications network need to reach a PoP node and then perform relay transmission, the hop count that the transmitted data packets are forwarded is increased. Additionally, the PoP node needs to forward lots of data packets having a destination address that is in a network segment covered by stored routes of the super prefix, which raises very high requirements for forwarding capability of the PoP node. When the number of the forwarded data packets is too large, breakdown of the PoP node might Occur.